Electric machines in which the turns of a coil cut through a mechanical field have heretofore generally utilized permanent magnets and/or electromagnets to produce the field and coils which cut through the magnetic field generated by the permanent magnets and/or electromagnets and have been constructed so as to maximize the number of turns which can intercept the lines of force transversely.
Such machines, for example, electric motors, can have the poles of the stator magnets so positioned that the lines of force between them run perpendicular or crosswise to the axis of the coil, i.e. approximately parallel to the plane of a turn of the coil.
Reference may be had in that regard to the following U.S. Pat. Nos.:
______________________________________ 3,602,749 3,287,676 4,703,212 3,836,801 3,828,213 3,883,633. ______________________________________
These principles apply not only to the rather complex arrangements of rotor coils (armature coils) and stator magnets described in these patents but also to systems in which the stator magnets can lie in axial planes of the rotor or armature or which can have their opposite poles in such planes so that the major direction of the lines of force between the opposite poles of a given magnet is parallel to the axis of the armature.
There are motor arrangements known in which the opposite poles of the magnet are spaced apart in the peripheral direction, i.e. are angularly spaced about the axis of the rotor in a plane which is perpendicular to the axis, i.e. a radial plane of the motor, but, in those cases, the coils tend to be wound so that their axes lie in axial planes and are perpendicular to the axis of the rotor.
With all of these arrangements the so-called back electromagnetic force (back EMF) is high and as a consequence, to provide the requisite torques, high voltages must be applied to secure the necessary power output.
Furthermore, these earlier systems are characterized by a high degree of induction and substantial stray induction which can lead to direct current losses and excess heating of the motor.